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A264545
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Number of (n+1)X(3+1) arrays of permutations of 0..n*4+3 with each element having directed index change -1,1 -1,2 1,0 or 0,-1.
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1
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1, 6, 16, 45, 133, 400, 1204, 3561, 10554, 31493, 93784, 278862, 829809, 2469737, 7349616, 21870896, 65083321, 193678264, 576359005, 1715146434, 5103989104, 15188659597, 45198999981, 134504868528, 400264674436, 1191122820729
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) +10*a(n-3) -4*a(n-4) +8*a(n-5) -25*a(n-6) -4*a(n-8) +33*a(n-9) +4*a(n-10) -4*a(n-11) -10*a(n-12) -2*a(n-13) +a(n-15)
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EXAMPLE
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Some solutions for n=4
..1..2..5..6....1..2..3..5....1..2..3..5....1..4..3..6....1..2..3..5
..0..8..9..3....0..6..7.10....0..8..9.10....0..8..2.10....0..6..7..9
..4.10.12..7....4.12.11.14....4.12..6..7....9..5.12..7....4.10.11.14
.13.14.16.11....8..9.16.18...13.14.16.11...13.14.16.11....8.16.17.18
.17.18.19.15...17.13.19.15...17.18.19.15...17.18.19.15...12.13.19.15
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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